Recently, many friends have asked me about the problem of floating mud in the secondary sedimentation tank. Today, let's have a good chat. Floating mud in the secondary sedimentation tank is not a small matter, it directly affects water quality and may even cause chaos in the entire sewage treatment system. What are the reasons that caused mud to float in the secondary sedimentation tank? How can we solve it?
Sludge aging
Let's first take a look at the aging of sludge. It's like when a person gets old, their physical functions decline, the sludge 'gets old', and their activity decreases. At this point, the settling performance of the sludge deteriorates and it is easy to float up. Usually, in this situation, you can see that the color of the sludge has darkened and there is no luster, like an old man without energy.
Why does sludge age? The main reason is that the sludge stays in the aeration tank for too long and the nutrients cannot keep up. Microorganisms have always been in a state of "not being able to eat enough and being exhausted", which means they are aging.
To solve the problem of sludge aging, it is necessary to discharge the sludge appropriately to keep the sludge in the aeration tank "youthful and energetic". At the same time, according to the water quality, it is necessary to supplement nutrients reasonably, such as nitrogen and phosphorus, which cannot be lacking. Just like a person needs to eat enough to have the strength to work, microorganisms also need to eat and drink well to work properly.
sludge bulking
Sludge expansion is also a common cause of floating sludge in secondary sedimentation tanks. Sludge expansion can be divided into filamentous bacterial expansion and non filamentous bacterial expansion. When filamentous bacteria expand, they multiply in large numbers in the sludge, stirring it up like a tangled mess. If it cannot settle, it will float up. The expansion of non filamentous bacteria is usually caused by sudden changes in the incoming water quality, such as sudden changes in pH value, high or low water temperature.
When sludge swelling is discovered, it is necessary to first determine which type it is. If the filamentous bacteria expand, you can add some sodium hypochlorite to the aeration tank to control the number of filamentous bacteria, but this trick needs to be used carefully, adding too much will also kill normal microorganisms. For the expansion of non filamentous bacteria, it is necessary to quickly adjust the inlet water quality and control the pH value and water temperature within the appropriate range.
Excessive hydraulic load
Simply put, excessive hydraulic load means that too much and too fast water enters the secondary sedimentation tank, exceeding its processing capacity. Like a small water pipe, if you insist on letting it pass through a large amount of water in a short period of time, it will definitely overflow. The same goes for the secondary sedimentation tank. When the water comes too quickly, the sludge is carried away by the water flow before it can settle and float on the surface of the water.
To solve the problem of excessive hydraulic load, it is necessary to optimize the inflow rate, ensure even inflow, and avoid excessive and insufficient flow. It is also possible to consider renovating the secondary sedimentation tank by increasing its volume or improving its internal structure to enhance sedimentation efficiency.
Dissolved oxygen problem
Dissolved oxygen is important for microorganisms. If the dissolved oxygen in the aeration tank is too low, microorganisms will not be able to properly decompose pollutants, and the sludge performance will deteriorate, making it easy to float. On the contrary, if the dissolved oxygen is too high, it will also disperse the sludge, leading to difficulties in settling.
Controlling dissolved oxygen requires adjusting the aeration rate. An online dissolved oxygen monitoring device can be installed to monitor the real-time situation of dissolved oxygen, adjust the aeration equipment according to the data, and keep the dissolved oxygen at an appropriate level, generally controlled at 2-4mg/L.
The reasons and solutions for floating mud in the secondary sedimentation tank are roughly as follows. Don't panic when encountering mud drifting problems. Follow the instructions above to investigate the cause step by step and then solve it specifically. The issue of sewage treatment requires more observation and analysis. We hope that everyone's sewage treatment system runs smoothly and the effluent quality meets the standard steadily!
